RS Aggarwal Solutions for Class 9 Chapter 17 “Bar-graph-histogram-and-frequency-polygon”, a histogram is a graph that illustrates the relative frequency or probability density of a single variable and relative frequency polygon. A frequency polygon is almost identical to a histogram, which is used to compare sets of data or to display a cumulative frequency distribution. It uses a line graph to represent quantitative data. Tables, graphs, pie-charts, bar graphs, histograms, polygons etc. are used to describe statistical data pictorially. A relative frequency polygon has peaks that represent the percentage of total data points falling within the interval. Bar graphs are used to compare various details; histograms are used to summarise continuous data and frequency polygons help in understanding the shapes of distribution.